x^(n-1).(x+y)-y.[x^(n-1) + y^(n-1)]
=x.x^(n-1)+y.x^(n-1)-y.x^(n-1)-y.y^(n-...
= x. x^n:x - y.y^n:y
=x^n - y^n
xn-1(x+y)-y(xn-1+yn-1)
= xn+xn-1y-yxn-1-yn
=xn+(xn-1y-yxn-1)-yn
=xn-yn
xn – 1 (x + y) – y(xn – 1 + yn – 1)
=xn+ xn – 1y – yxn – 1 - yn
= xn + xn – 1y - xn – 1y - yn
= xn – yn.
\(x^{n-1}\left(x+y\right)-y\left(x^{n-1}+y^{n-1}\right)\)
\(=x^{n-1}.x+x^{n-1}.y-y.x^{n-1}-y.y^{n-1}\)
\(=x^n-y^n\)